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Biomedical subjects

C A Mitchell

Publications and source records attributed to C A Mitchell.

At least 253 records · Page 14Linked to original sources

Fusion between myogenic cells in vivo: an ultrastructural study in regenerating murine skeletal muscle.

Fusion of myogenic cells in adult murine skeletal muscle regenerating in vivo was examined at the ultrastructural level. Fusion of myoblast to myoblast, myoblast to myotube, and myotube to myotube was observed by 4 to 5 days after injury. Fusion between myogenic cells (myoblasts or myotubes) lacking a definitive glycocalyx or external lamina (basal lamina) occurred at multiple sites. It was defined by zones of cytoplasmic confluence between apposed cells at sites where contiguous segments of the cell membranes were interrupted while their edges had united resulting in linear continuity; vesicles of varying dimensions were frequent in these areas of fusion. Myoblasts were seen invaginating the surface of myofibres and again vesicles were seen in abundance in such regions. Cilia were often observed at this junctional zone suggesting that they might play a role in fusion. In the one example of probable fusion between a myotube and a myofibre, only a single area of cytoplasmic continuity was apparent.

Animals↗

Geriatric trauma: a case study.

Major advances in health care have made it possible for a greater number of people to live to advanced age and thereby be exposed to the same risk of injury as the younger segment of the population. Elderly trauma victims, however, possess unique needs that must be addressed. Comorbidity, the aging process, and its relationship to the response to injury, as well as ethical and moral dilemmas such as "do not resuscitate" decisions and cost of care, need to be investigated. Although advanced age clearly predisposes one to an increase in mortality, mortality has also been correlated with complications that develop during the hospital stay. Trauma, especially involving the elderly, is a rich area for nursing research, and a refined knowledge base contributes to improving the quality of trauma care.

Aged↗

Current procedures for diagnosing dysphagia in elderly clients.

Intubation no longer remains the only solution to feeding problems of the elderly patient with dysphagia. Dysphagic disorders result from neurogenic, myogenic, psychogenic, or mechanical causes. Thus numerous hospitalized or institutionalized elderly patients may have dysphagic symptoms. The consequences of this disorder are significant, and aspiration pneumonia is often the outcome. Current diagnostic procedures available to identify dysphagia are discussed.

Aged↗

Respiratory effects of occupational exposure to an epoxy resin system.

A standardized respiratory questionnaire and pulmonary function tests were used to examine thirty-four employees of a snow-ski manufacturing plant, including twenty-five workers who were exposed to an epoxy resin system containing the amine hardener 3-dimethylamino propylamine (3-DMAPA). Maximum expiratory flow-volume curves were obtained on Monday and Thursday, before and after each shift, and FVC, FEV1.0, MEF50%, and MEF25% were caculated. Environmental measurements of the total amine levels were found to range from 0.41 to 1.38 ppm. The group with the greatest exposure (0.55-1.38 ppm) showed significant decreases in lung function over Monday and over the week. Although all employees in this group showed decreases in pulmonary function, acute changes were greater in present cigarette smokers and in subjects who reported respiratory symptoms upon exposure to the epoxy resin system. There was no evidence of permanent loss of lung function in subjects with either the highest or longest exposure.

Adult↗

Importance of the indoor environment in air pollution exposure.

A portable personal air pollution sampler was used to measure the exposure of twenty children to respirable particulates, sulfur dioxide, and nitrogen dioxide over a 24-hour period. Particulate exposures were significantly higher among children who lived with one or more smokers, and exceeded the primary air quality standard in nineteen of the twenty subjects. To a large extent, an individual's respirable particulate load appears to be determined by exposure to indoor rather than outdoor pollutants.

Adolescent↗

Evaluation of outdoor air quality in rural and urban communities.

A year-round air monitoring program for sulfur dioxide, sulfates, nitrogen dioxide, nitrates, ozone, and total suspended particulates was conducted in three towns with population densities ranging from 29/km2 to 1178/km2. The results showed significant differences in concentrations of several pollutants between the urban town and the two rural towns. However, site-to-site variation over distances of 1 mile or less within the urban area was considerable. To express pollutant loads in each town in a single number, we calculated a combined pollutant index on premises similar to those used for combined occupational exposures, but with U.S. primary air quality standards rather than threshold limit values as indices of minimal health effects. The combined index exceeded unity in all three towns, suggesting either that total pollutant loads may be excessive even in the sparsely populated town of Lebanon, Connecticut, or, more likely, that the U.S. primary air quality standards have been set at low levels without due regard for additive effects.

Air Pollutants↗

Daily variation in air quality.

We related year-round air pollutant concentration in three small U.S. towns, with considerable differences in population density and industrial activity, to air temperature, wind direction, wind speed, rainfall, sky conditions, and days of the week (workdays vs. pended particulates) concentrations can be explained by changes in weather conditions. During weekends, pollution did not decrease consistently and, in some instances, may have increased as a result of dense recreational traffic. We suggest that recognition of the multifactorial causation of high levels of air pollution may lead to more realistic, more effective, and less costly air pollution ocntrol programs.

Air Pollutants↗

A case study of an abused older woman.

Because little is known about elder abuse, it is difficult to propose strategies for primary prevention or to select the most efficacious strategies to deal with abuse. Intervening is also complicated by personal and professional values that often have their origin in one's own family. Elder abuse is a complex challenge to health professionals, making assessment, diagnosis, treatment, and evaluation difficult. Using a case study approach, we illustrate these complexities, describe the dynamics, and apply a decision-making model to the management of a case of abuse. Theoretical research and background information are woven into the discussion of the case to explain further the dynamics.

Aged↗

Calcium bioavailability of vegetarian diets in rats: potential application in a bioregenerative life-support system.

Calcium bioavailability of vegetarian diets containing various proportions of candidate crops for a controlled ecological life-support system (CELSS) was determined by femur 45Ca uptake. Three vegetarian diets and a control diet were labeled extrinsically with 45Ca and fed to 5-wk old male rats. A fifth group of rats fed an unlabeled control diet received an intraperitoneal (IP) injection of 45Ca. There was no significant difference in mean calcium absorption of vegetarian diets (90.80 +/- 5.23%) and control diet (87.85 +/- 5.25%) when calculated as the percent of an IP dose. The amounts of phytate, oxalate, and dietary fiber in the diets did not affect calcium absorption.

Absorption↗

Audit of consultant physicians' reply letters for referrals to clinics in a tertiary teaching hospital.

BACKGROUND: Doctors referring patients to consultant physicians seek reply letters which both educate and assist in ongoing patient management. Highly desirable attributes in specialist letters include clearly stated and justified: (i) diagnostic formulations, (ii) management regimens, (iii) use of clinical investigations, (iv) prognostic statements, (v) contingency plans and (vi) follow-up arrangements. AIM: To explicitly evaluate the quality of reply letters for new patients referred to clinics at a tertiary teaching hospital. METHODS: Letters were sampled from outpatient clinics of 10 different medical specialties at Princess Alexandra Hospital in Brisbane, Australia. Reply letters for new patient referrals between 1 August 2000 and 31 October 2000 were retrieved, from which data were abstracted to calculate the proportion of letters satisfying prespecified quality attributes. RESULTS: Of 297 new patient referrals, reply letters were retrieved for 204 (69%). Of these, 147 (72%) referrals were accompanied by a referral letter, mostly (113/147; 77%) from general practitioners. For 120 referrals involving diagnostic issues, 69 (56%) letters stated a diagnostic formulation. Of 114 letters recommending further clinical investigations, 61 (53%) described a rationale for such testing. In 125 cases where therapy was a key issue, 83 (66%) letters recommended changes to current treatment for which reasons were specified in 46 (55%) cases, and contingency plans provided in 13 (16%). Prognosis was mentioned in only 18 (9%) cases. Follow-up arrangements were detailed in 123 (60%) letters. Assessments of patient understanding and likely adherence to therapy were stated in less than 15% of -letters. CONCLUSIONS: Opportunities exist for improving quality of consultant physicians' reply letters in terms of greater use of problem lists, contingency plans, prognostic statements and patient-centred assessments, as well as more frequent enunciation of consultants' reasoning behind requests for further tests and changes to current management. Use of structured letter templates may facilitate more consistent inclusion of key information to referring doctors.

Australia↗

Effects of physical agitation on yield of greenhouse-grown soybean.

Agronomic and horticultural crop species experience reductions in growth and harvestable yield after exposure to physical agitation (also known as mechanical stress), as by wind or rain. A greenhouse study was conducted to test the influence of mechanical stress on soybean yield and to determine if exposure to mechanical stress during discrete growth periods has differential effects on seed yield. A modified rotatory shaker was used to apply seismic (i.e., shaking) stress. Brief, periodic episodes of seismic stress reduced stem length, total seed dry weight, and seed number of soybean [Glycine max (L.) Merr.]. Lodging resistance was greater for plants stressed during vegetative growth or throughout vegetative and reproductive growth than during reproductive growth only. Seed dry weight yield was reduced regardless of the timing or duration of stress application, but was lowest when applied during reproductive development. Seismic stress applied during reproductive growth stages R1 to R2 (Days 3 to 4) was as detrimental to seed dry weight accumulation as was stress applied during growth stages R1 to R6 (Days 39 to 42). Seed dry weight per plant was highly correlated with seed number per plant, and seed number was correlated with the seed number of two- and three-seeded pods. Dry weight per 100 seeds was unaffected by seismic-stress treatment. Growth and yield reductions resulting from treatments applied only during the vegetative stage imply that long-term mechanical effects were induced, from which the plants did not fully recover. It is unclear which yield-controlling physiological processes were affected by mechanical stress. Both transient and long-term effects on yield-controlling processes remain to be elucidated.

Physical Stimulation↗

Photoperiod shift effects on yield characteristics of rice.

Edible yield must be maximized for each crop species selected for inclusion in the Controlled Ecological Life-Support System (CELSS) proposed by NASA to support long-term manned space missions. In a greenhouse study aimed at increasing biomass partitioning to rice (Oryza sativa L.) grain, plants of the high yielding semi-dwarf rice cultivar Ai-Nan-Tsao were started in pots under 8-h photoperiods at a density of 212 plants m-2. After different periods of time under 8-h photoperiods, pots were switched to continuous light for the remainder of the cropping cycle. Continuous light did not delay time to first panicle emergence (60 d) or time to harvest (83 d). There was a positive correlation between the length of continuous light treatments and nongrain biomass. Grain yield (1.6 +/- 0.2 g plant-1) did not increase in continuous light. Yield-efficiency rate (grain weight per length of cropping cycle, canopy volume, and weight of nongrain shoot biomass) was used to compare treatments. Small Ai-Nan-Tsao rice canopies grown under 8-h photoperiods were more efficient producers of grain than canopies grown under continuous light for a portion of the rice cropping cycle.

Biomass↗

Buteyko breathing techniques in asthma: a blinded randomised controlled trial.

OBJECTIVE: To evaluate the effect of Buteyko breathing techniques (BBT) in the management of asthma. DESIGN: Prospective, blinded, randomised study comparing the effect of BBT with control classes in 39 subjects with asthma. The study was conducted from January 1995 to April 1995. PARTICIPANTS AND SETTING: Subjects recruited from the community, aged 12 to 70 years, with asthma and substantial medication use. MAIN OUTCOME MEASURES: Medication use; morning peak expiratory flow (PEF); forced expiratory volume in one second (FEV1); end-tidal (ET) CO2; resting minute volume (MV); and quality of life (QOL) score, measured at three months. RESULTS: No change in daily PEF or FEV1 was noted in either group. At three months, the BBT group had a median reduction in daily beta 2-agonist dose of 904 micrograms (range, 29 micrograms to 3129 micrograms), whereas the control group had a median reduction of 57 micrograms (range, -2343 micrograms to 1143 micrograms) (P = 0.002). Daily inhaled steroid dose fell 49% (range, -100% to 150%) for the BBT group and 0 (range, -82% to +100%) for the control group (P = 0.06). A trend towards greater improvement in QOL score was noted for BBT subjects (P = 0.09). Initial MV was high and similar in both groups; by three months, MV was lower in the BBT group than in the control group (P = 0.004). ET CO2 was low in both groups and did not change with treatment. CONCLUSION: Those practising BBT reduced hyperventilation and their use of beta 2-agonists. A trend toward reduced inhaled steroid use and better quality of life was observed in these patients without objective changes in measures of airway calibre.

Adolescent↗

Monocrotophos and dicrotophos residues in birds as a result of misuse of organophosphates in Matagorda County, Texas.

About 1100 birds of 12 species died from organophosphate poisoning in Matagorda County on the Texas Gulf Coast in March and May 1982. Birds died from feeding on rice seed that was illegally treated with dicrotophos or monocrotophos and placed near rice fields as bait to attract and kill birds. Brain acetylcholinesterase inhibition of affected birds averaged 87% (range 82-89%), and contents of gastrointestinal tracts contained residues of dicrotophos (5.6-14 ppm) or monocrotophos (2.1-13 ppm). Rice seed collected at mortality sites contained 210 ppm dicrotophos or 950 ppm monocrotophos. Mortality from dicrotophos poisoning continued for almost 3 weeks. The practice of illegally treating rice seed with either of these 2 organophosphates appears to be infrequent but widespread at present.

Animals↗